新疆东天山白山钼矿深部岩体地球化学特征及成因意义  

Geochemistry and petrogenesis of core samples from Baishan molybdenum deposit, East Tianshan Mountains, Xinjiang

作　　者：朱志敏[1,2] 熊小林[3] 初凤友[1] 吴云辉[2] 

机构地区：[1]国家海洋局第二海洋研究所,国家海洋局海底科学重点实验室,杭州310012 [2]中国科学院广州地球化学研究所,矿物学与成矿学重点实验室,广州510640 [3]中国科学院广州地球化学研究所,同位素地球化学国家重点实验室,广州510640

出　　处：《岩石学报》2013年第1期167-177,共11页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划项目(2007CB411303);国家自然科学杰出青年基金项目(40825010);国家自然科学青年基金项目(40906037)联合资助

摘　　要：白山钼矿深部钻探表明矿体下部存在着矿化花岗斑岩体,所获岩芯显示其岩性主要为似斑状钾长花岗岩、黑云母斜长花岗岩和花岗斑岩。该岩体具有高Al、Na和Sr,低Mg、Y和Yb,以及高Sr/Y和La/Yb比值等特点,类似于埃达克质岩的地球化学特征,暗示来源于较深的含石榴子石的源区;岩石形成时代和地球化学构造判别图解表明,岩体形成于造山后的构造环境。因此,白山钼矿岩体可能为加厚下地壳熔融的产物。白山钼矿床的成矿作用可能与埃达克质岩浆活动有关,其成矿过程得益于高Mo丰度的地壳源区、成岩过程中提供流体和岩浆高氧逸度环境等。Samples from deep drill holes show that the mineralized granitic rocks related to Baishan molybdenum deposit, East Tianshan Mountains, Xinjiang are moyite, biotite-plagiogranite and granitic porphyry. The collected samples were used to investigate their geochemical features and petrogenesis for these rocks.All of the rocks are characterized by high Al2O3 and Na2O and Sr contents, but low MgO, Y and Yb contents and high Sr/Y and La/Yb ratios, similar to the geochemical characteristics of adakitic rocks. These signatures suggest that the magmas of these rocks were derived from a deep garnet-bearing source. Evidence of rock ages and geochemical tectonic-discrimination-diagrams show these rocks were formed in post-orogenic environment. Based on the geochemical characteristics, we proposed that the magmas of these adakitic rocks （drill hole core samples） may have been formed by partial melting of the thickened lower crust. The mineralization of Baishan molybdenum deposit should be related to adakitic magma activity. The high Mo abundance of the crustal source, the fluid release from the magmas and high oxygen fugacity environment during the magmatic process may be the key factors for the molybdenum mineralization.

关 键 词：地球化学 花岗斑岩体 埃达克质岩 白山钼矿 东天山 

分 类 号：P588.121[天文地球—岩石学]